1. Field of the Invention
This invention relates to structures and methods for fabricating perpendicular write heads. More specifically, the invention relates to improved methods for fabricating notched trailing shields using metallic CMP stop layers to improve yields within wafer and wafer to wafer.
2. Description of the Related Art
Perpendicular write heads are currently well known in the art. A particular variant of such heads, known as the perpendicular write head with a notched trailing shield, has also been recently disclosed. See, for example US Patent Application Publications 2005/0264931, 2006/0023352, 2005/0190491, and 2005/0068671, all assigned to Hitachi Global Storage Technologies, Netherlands B.V. During the fabrication of the notched trailing shield, the tapered write pole is produced by ion milling, and the area around and above the tapered pole is filled with alumina. The alumina deposition leaves a “bump” or high spot directly above the tapered pole which must be removed to create a notch directly above the pole. The trailing shield layer is then deposited above the pole and within the notch. Removal of the “bump” is typically done with a CMP process. However, the CMP process may produce rounding and damage to the region proximate to where the notch is formed, altering the critical gap thickness and producing non-planar trailing shields. What is needed is a better process for producing the notched trailing shield for the perpendicular write head.
United States Patent Application Publication 2005/0264931 discloses fabrication of a perpendicular write head in a wafer, wherein at least two sides of a write pole are defined (e.g. by ion milling) while a third side of the write pole is protected by a masking material. At this stage, a material that is to be located in the write gap is already present between the write pole and the masking material. After definition of the write pole surfaces, a layer of dielectric material is deposited. During this deposition, the masking material is still present. Thereafter, the masking material (and any dielectric material thereon) is removed, to form a hole in the dielectric material. Next, a trailing shield is formed in the structure, so that at least one portion of the trailing shield is located in the hole, and another portion of the trailing shield is located over the dielectric material, in an area adjacent to the hole. Note that the gap material is now sandwiched between the portion of the trailing shield in the hole, and the write pole.
United States Patent Application Publication 2005/0259355 discloses a perpendicular write head including a main pole and a trailing shield, the main pole being made of a diamond-like carbon (DLC) layer as hard mask and a rhodium (Rh) layer as shield gap, both DLC and Rh layers being CMP stop layers so as to avoid corner rounding and damage from chemical mechanical planarization (CMP) process, the DLC layer being removed by reactive ion etching (RIE) to create a trench, the trailing shield being deposited into the trench for self alignment.
United States Patent Application Publication 2006/0023352 discloses a method and apparatus for providing a reverse air bearing surface head with trailing shield design for perpendicular recording. A reverse air bearing surface head for perpendicular recording is provided with an inversed bevel shape to handle skew when recording data on a magnetic recording medium.
United States Patent Application Publication 2005/0190491 discloses a perpendicular magnetic write head having a notched, self aligned trailing shield for canting a magnetic field emitted there from.
United States Patent Application Publication 2005/0068671 discloses a magnetic transducer with separated read and write heads for perpendicular recording. The write head has a trailing shield that extends from the return pole piece toward the main pole piece to form the write gap at the air-bearing surface. One embodiment of the trailing shield is a two part structure with a pedestal and a much smaller tip that confronts the main pole piece at the gap. In one embodiment a sink of non-magnetic, electrically conductive material is disposed in the separation gap between the read head and the flux bearing pole piece. The sink is preferably made of copper and does not extend to the ABS.
United States Patent Application Publication 2005/0102820 discloses that conventional liftoff processes used to define track width in magnetic read heads can produce an uneven etch-depth of dielectric materials around the sensor and cause shorting to the overlay top lead layer. This problem has been overcome by printing the images of track width and stripe height onto an intermediate layer to form a hard mask. Through this hard mask, the GMR stack can be selectively etched and then back-filled with a high-resistivity material by using newly developed electroless plating processes.
United States Patent Application Publication 2005/0068665 discloses a method and materials to fabricate a trailing shield write pole that resolve the problems of controlling the write gap and preventing damages to the write gap or pole during fabrication of the subsequent structure: This process also introduces a CMP assisted lift-off process to remove re-deposition and fencing (increase yields) and a method to create dishing in the top of the write pole. Moreover, also included in this disclosure are suitable materials that can function as an ion mill transfer layer, CMP layer, and RIEable layer.
United States Patent Application Publication 2004/0012894 discloses a magnetic head including a substrate and a data transducer positioned upon the substrate. The data transducer includes a reader comprised of a top shield and a bottom shield characterized by at least one of the shields including a layer for compensating a thermally-caused expansion of the reader.
U.S. Pat. No. 6,757,141 discloses a perpendicular recording head having a second pole piece which includes a bottom ferromagnetic shaping layer and a top ferromagnetic probe layer. Each of these layers has a flare point where the layers first commence to widen after the ABS with the flare point of the shaping layer being located between an air bearing surface (ABS) of the head and the flare point of the probe layer. Further, the probe layer has a probe at the ABS which has a decreasing width from its top to its bottom to provide a trapezoidal shape which minimizes side writing due to skew of the probe at outermost and innermost circular tracks of a rotating magnetic disk.